Problem: The geometric sequence $(a_i)$ is defined by the formula: $a_i = -2 \left(\dfrac{1}{2}\right)^{i - 1}$ What is $a_{2}$, the second term in the sequence?
From the given formula, we can see that the first term of the sequence is $-2$ and the common ratio is $\dfrac{1}{2}$ The second term is simply the first term times the common ratio. Therefore, the second term is equal to $a_2 = -2 \cdot \dfrac{1}{2} = -1$.